Turbosupercharger



March 27, 1945. J 5, ALFORD 2372 45? TURBCSUPERCHARGER Filed Feb. 4, 1944 SL/PSTREAM ENG/NE E X HA U5 T Inventor: Joseph SAHord,

b Z/ 6. y H i gzttorney.

Patented Mar. 27, 1945 2,372,467 TURBOSUPERCHARGER Joseph S. Alford, Nahant, Mass, assignor to General Electric Company, a corporation of New York Application February 4, 1944, Serial No. 521,121

1 Claim.

The present invention relates to turbosuperchargers for aircraft comprising an exhaust gasoperated turbine having a bucket wheel secured to an overhung shaft and a compressor driven by the turbine for supplying compressed air to a combustion engine, a cabin or like consumer for compressed air. More specifically, the invention relates to arrangements for protecting and cooling the turbine wheel such as are disclosed, for

example, in the application of C. W. Smith, Se-.

rial No. 281,562, filed June 28, 1939, and assigned to the same assignee as the present application. Difllculties have heretofore been experienced in the cooling of such bucketwheels by means of cooling caps and like devices arranged to receive cooling air from the slipstream and force it towards the disk and rim of the bucket wheel. Such difilculties occur especially in installations -in which the cooling cap and the bucket wheel "tively cooled during any operating condition.

This is accomplished in accordance with my invention by the provision of a cooling cap or to the device provided with an inlet conduit for receiving air from the slipstream together with means such as an injector in said inlet conduit arranged to receive compressed medium discharged irom the compressor to impel the air from the slipstream into the cooling cap.

For a better understanding of what I believe to be novel and my invention, attention is directed to the following description and the claim appended thereto in connection with the accompanying drawing.

n the drawing Fig. 1 illustrates a turbosupercharger embodying my invention and Fig. 2 shows a modification of my invention.

The arrangement of Fig. 1 comprises a turbine having a bucket wheel Ill secured to an overhung shaft II and a nozzle box l2 with a row of nozzle passages ill for conducting operating gases to the bucket wheel ID. The nozzle box is connected to a conduit I4 for receiving exhaust gases from an engine exhaust manifold. A waste conduit P5 with a waste gate i6 is connected to the nozzle box to discharge some of the gases therefrom directly to atmosphere and thereby to control the output of the turbine.

A centrifugal type compressor i1 is arranged to be driven from the bucket wheel l0 and has an inlet conduit ill with a ram IQ for receiving air from the slipstream and a discharge conduit for conducting compressed air through an intercooler 2| to the carburetor of an internal combustion engine. The impeller of the compressor is secured to another overhung portion of the shaft H, which latter is supported by a bearing 22 located between the compressor and the turbine.

A cooling cap 23 is arranged on the outlet side of the bucket wheel ill to protect thedisk of the wheel from the hot gases discharged from the bucket passages and effectively to cool the rim of the disk near the roots of the buckets secured thereto. The cooling cap has a curved disk 24 arranged adjacent and closely spaced with the rim of the bucket wheel disk. A streamlined conduit 25 is secured to the disk 24 across a diameter thereof. The conduit 25 has an inlet portion 26 for receiving cooling air and together with the disk 24 forms a discharge nozzle 2'! near the rim of the bucket wheel disk and the roots of the buckets attached thereto. The cooling cap is supported on the nozzle box by means of two brackets 28 and 29. During operation a continuous stream of cooled air is discharged from the nozzle 21 towards the rim of the bucket wheel disk.

In order to reduce heat transfer from the nozzle box towards the bearing 22 and the compressor casing a curved annular partition 30 is disposed between the compressor casing and the nozzle box in spaced relation with them and the bearing 22. The partition is suitably supported in known manner on the compressor casing. Thus, two annular spaces 3| and 32 are formed between the partition 30 and the compressor casing and the nozzle box respectively.

The arrangement so far described may be considered typical of a turbosupercharger provided with means for cooling the turbine bucket wheel.

As pointed out above, the dynamic pressure produced by the slipstream is often not sufilcient to force a substantial amount of cooling air through the cooling cap and also through the annular spaces 3| and 32 formed on opposite sides of the partition 30. Therefore, according to my invention, auxiliary means are provided for injecting air from the slipstream into the cooling cap and also the cooling spaces 3|, 32. This auxiliary means in the present example uses compressed air from the compressor and is combined with the intercooler 2|. The intercooler is of the surface type and has a plurality of cooling tubes or channels 33 with inlets connected to a ram 34 for receiving air from the slipstream and outlets connected to a conduit 35 which has a discharge opening 36 for discharging part of the cooling air into the atmosphere in the direction of the slipstream. Some of the air in the conduit 35 is discharged therefrom through injectors 31 and 38, each having an inlet connected to the conduit 35. The outlet of the injector 31 is connected to the space 3| and the outlet of the injector 38 is connected to the inlet portion 26 of the conduit of the cooling cap. The injectors 31 and 38 are provided with nozzles 39 and 40 connected to receive compressed air from the discharge conduit 20 of the compressor to impel the air from the slipstream.

The space 3| is substantially closed by an outer wall 4| connected between the compressor casing and the partition 30. Thus, cooling air injected into the space 3| from the injector 31 flows along the bearing 22 towards the inlet side of the bucket wheel I0 and around the edge of the curved portion of the partition into the space 32, whence it is discharged to atmosphere.

Cooling air injected through the injector 38 into the cooling cap is discharged from the nozzle 21 towards the rim of the bucket wheel disk, whence it may be directed to atmosphere together with the gases discharged from the wheel.

In the arrangement described above the cooling air for the turbine is taken from the conduit after it has passed through the intercooler 2|. In many instances this air may have been heated too much in the intercooler to assure effective cooling of the turbine, particularly the bearing 22. Likewise, the primary air for impelling the;

air from the slipstream is taken from the conduit 20 at a point ahead of the intercooler as regards the direction of flow therethrough. This compressed air in some instances may cause substantial heating of the air from the slipstream in the injectors 31, 38. Therefore in some cases it may be desirable to provide an arrangement as shown diagrammatically in Fig. 2 comprising a compressor driven by an exhaust gas-operated turbine 46. The compressor has a discharge conduit ,4! connected to an intercooler 48 corresponding to the intercooler 2| of Fig. 1. Cooling air is conducted to the turbine by injectors 49 and 50, corresponding to the injectors 31 and 38 of Fig. 1 respectively. Air is conducted to the intercooler 48 by a conduit 5| which has an inlet or ram 52 arranged to receive air from the slipstream. The conduit 5| has a branch connected to the intercooler 48. Upon passage through said intercooler the air is discharged into the slipstream by a discharge conduit 53. Another branch of the conduit 5| is connected to the injectors 49 and 50. Thus, air is directly conducted from the slipstream through the conduit 5| to the injectors 49, without passing through the intercooler 48. The primary air for impelling the slipstream air in the injectors 49, 50 is conducted thereto by means of nozzles 54 and 55, corresponding to the nozzles 39, 40 of Fig. 1 respectively. The nozzles 54, 55 are connected to branches of a conduit 56 which is connected to the compressor discharge conduit 41 at a point beyond the intercoolers as regards the direction of flow therethrough. Each of the branches of the conduit 56 includes a valve 51 and 58 respectively for controlling the fiow of air therethrough.

Having described the method of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, I wish to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

Turbosupercharger for aircraft comprising an exhaust gas-operated turbine having a bucket .wheel, a shaft with an overhung portion supporting the wheel, a bearing for the shaft, and a nozzle box concentrically spaced from the bearing for conducting gases to the wheel, a centrifugal type compressor having an impeller driven from another overhung portion of the shaft, a partition located between the nozzle box and the conipressor and having a curved portion with an edge closely spaced from the bucket wheel, an

intercooler connected to the outlet of the compressor, means including a ram for conducting cooling air from the slip-stream to the intercooler, a conduit for receiving heated air from the intercooler, and means for cooling the bucket wheel comprising a cooling cap disposed on the discharge side of the bucket wheel and having a nozzle for discharging cooling air towards the bucket wheel and means for conducting cooling air to the cap and to the space formed between ,the partition and the compressor, said means comprising two injectors each having an inlet connected to said conduit and an outlet connected to the cooling cap and to said space respectively and conduit means connected to the outlet of the compressor ahead of the intercooler as regards the direction of flow therethrough for conducting compressed medium to said injectors.

JOSEPH S. ALFORD. 

